Load Switch Using Ground Pin as Positive Rail for Negative Input
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional integrated load switches require additional circuitry and pins for negative input applications, increasing cost and complexity.
Innovation Solution
An integrated circuit with a load switch that uses a negative input voltage, employing a level shifter and slew rate controller to control the load switch, where the ground pin acts as a positive supply rail and the input pin as an internal ground, allowing the load switch to operate efficiently with a negative voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional integrated load switches use both positive and negative supplies for negative input applications, then the load switch can operate with negative inputs, but additional pins and internal circuitry are required, increasing cost and complexity
Solution Approach 1:
The patent inverts the conventional approach by using the ground pin as a positive supply rail and the negative input pin as an internal ground reference. This inversion allows the load switch to handle negative inputs without requiring additional positive and negative supply pins, thereby reducing pin count and circuit complexity while maintaining the capability to operate with negative input voltages
Solution Approach 2:
The patent makes existing pins perform multiple functions: the ground pin serves as both ground and positive supply rail, while the negative input pin serves as both input and internal ground reference. This multi-functionality eliminates the need for dedicated positive and negative supply pins, reducing overall device complexity while maintaining versatility for negative input applications
2Adaptability or versatility
If additional circuitry is added to support negative inputs in conventional load switches, then negative input capability is achieved, but manufacturing cost increases
Solution Approach 1:
The patent reduces manufacturing cost by making existing circuit elements perform multiple functions. The ground pin and negative input pin are repurposed to provide both supply and ground references, eliminating the need for additional dedicated supply circuitry and reducing the overall component count, which directly lowers manufacturing costs while maintaining negative input support capability
3Speed
If the load switch transitions rapidly between states, then switching speed is improved, but voltage spikes and inrush currents occur, causing reliability issues
Solution Approach 1:
The patent implements preliminary action by using a level shifter circuit to prepare and condition the control signal before it reaches the load switch. The level shifter translates the enable pin voltage to the appropriate internal ground reference, ensuring the load switch transitions smoothly and predictably, which prevents voltage spikes and inrush currents while maintaining reliable operation
Solution Approach 2:
The patent introduces a level shifter circuit as an intermediary between the enable pin and the load switch control node. This intermediary circuit conditions the control signal by referencing it to the internal ground (negative input pin), ensuring smooth transitions and preventing direct abrupt switching that would cause voltage spikes, thereby improving reliability without significantly compromising switching speed
Data Source
Figure 1
Figure 2
AI summary
A integrated circuit (IC) is provided. The IC generally comprises an enable pin VON, a ground pin GND, an input pin VIN, an output pin VOUT, a load switch Q7, and control circuitry 104. The load switch is coupled between the input pin and the output pin and receives a negative voltage through the input pin. The control circuitry is coupled to the enable pin, the ground pin, and the load switch so as to control the load switch and to use the ground pin as a positive supply rail and the input pin as an internal ground.